Prebiotic levan type fructan from Bacillus subtilis PR-C18 as a potent antibiofilm agent: Structural elucidation and in silico analysis.

The global demand for therapeutic prebiotics persuades the quest for novel exopolysaccharides that can retard the growth of pathobionts and healthcare-associated pathogens. In this regard, an exopolysaccharide (3.69 mg/mL) producing strain showing prebiotic and antibiofilm activity was isolated from indigenous pineapple pomace of Tripura and identified as Bacillus subtilis PR-C18. Zymogram analysis revealed EPS PR-C18 was synthesized by levansucrase (∼57 kDa) with a maximal activity of 4.62 U/mg. Chromatography techniques, FTIR, and NMR spectral data revealed the homopolymeric nature of purified EPS with a molecular weight of 3.40 × 104 Da. SEM and rheological study unveiled its microporous structure and shear-thinning effect. Furthermore, EPS PR-C18 showed remarkable emulsification, flocculation, water retention, water solubilization, and antioxidant activity. DSC-TGA data demonstrated its high thermostability and cytotoxicity analysis verified its nontoxic biocompatible nature. In addition, the antibiofilm activity of EPS PR-C18 was validated using molecular docking, molecular simulation, MM-GBSA and PCA studies, which exhibited its strong binding affinity (-20.79 kcal/moL) with PelD, a virulence factor from Pseudomonas aeruginosa. Together, these findings support the future exploitation of EPS PR-C18 as an additive or adjuvant in food and pharmaceutical sectors.

Molecular insights into capsular polysaccharide secretion.

Capsular polysaccharides (CPSs) fortify the cell boundaries of many commensal and pathogenic bacteria1. Through the ABC-transporter-dependent biosynthesis pathway, CPSs are synthesized intracellularly on a lipid anchor and secreted across the cell envelope by the KpsMT ABC transporter associated with the KpsE and KpsD subunits1,2. Here we use structural and functional studies to uncover crucial steps of CPS secretion in Gram-negative bacteria. We show that KpsMT has broad substrate specificity and is sufficient for the translocation of CPSs across the inner bacterial membrane, and we determine the cell surface organization and localization of CPSs using super-resolution fluorescence microscopy. Cryo-electron microscopy analyses of the KpsMT-KpsE complex in six different states reveal a KpsE-encaged ABC transporter, rigid-body conformational rearrangements of KpsMT during ATP hydrolysis and recognition of a glycolipid inside a membrane-exposed electropositive canyon. In vivo CPS secretion assays underscore the functional importance of canyon-lining basic residues. Combined, our analyses suggest a molecular model of CPS secretion by ABC transporters.

Characterization and optimization of exopolysaccharide extracted from a newly isolated halotolerant cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1 with antiviral activity.

Several antiviral agents lost their efficacy due to their severe side effects and virus mutations. This study aimed to identify and optimize the conditions for exopolysaccharide (EPS) production from a newly isolated cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1, besides exploring its antiviral activity. The cyanobacterial EPS was purified through DEAE-52 cellulose column with a final yield of 83.75%. Different analysis instruments were applied for EPS identification, including Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and gas chromatographic-mass spectrometry (GC-MS). Plackett-Burman's design demonstrated that working volume (X1), EDTA (X2), inoculum size (X3), CaCl2 (X4), and NaCl (X5) are the most important variables influencing EPS production. Central composite design (CCD) exhibited maximum EPS yield (9.27 mg/mL) at a working volume of 300 mL in a 1 L volumetric flask, EDTA 0.002 g/L, inoculum size 7%, CaCl2 0.046 g/L, and NaCl 20 g/L were applied. EPS showed potent antiviral activities at different stages of herpes simplex virus type-1 and 2 (HSV-1, HSV-2), adenovirus (ADV) and coxsackievirus (A16) infections. The highest half-maximal inhibitory concentration (IC50) (6.477 µg/mL) was recorded during HSV-1 internalization mechanism, while the lowest IC50 (0.005669 µg/mL) was recorded during coxsackievirus neutralization mechanism.

Exopolysaccharide production by salt-tolerant bacteria: Recent advances, current challenges, and future prospects.

Natural biopolymers derived from exopolysaccharides (EPSs) are considered eco-friendly and sustainable alternatives to available traditional synthetic counterparts. Salt-tolerant bacteria inhabiting harsh ecological niches have evolved a number of unique adaptation strategies allowing them to maintain cellular integrity and assuring their long-term survival; among these, producing EPSs can be adopted as an effective strategy to thrive under high-salt conditions. A great diversity of EPSs from salt-tolerant bacteria have attracted widespread attention recently. Because of factors such as their unique structural, physicochemical, and functional characteristics, EPSs are commercially valuable for the global market and their application potential in various sectors is promising. However, large-scale production and industrial development of these biopolymers are hindered by their low yields and high costs. Consequently, the research progress and future prospects of salt-tolerant bacterial EPSs must be systematically reviewed to further promote their application and commercialization. In this review, the structure and properties of EPSs produced by a variety of salt-tolerant bacterial strains isolated from different sources are summarized. Further, feasible strategies for solving production bottlenecks are discussed, which provides a scientific basis and direct reference for more scientific and rational EPS development.

Characterisation of a capsular polysaccharide from Moraxella nonliquefaciens CCUG 348T.

Moraxella nonliquefaciens is a commensal of the human upper respiratory tract (URT) but on rare occasions is recovered in cases of ocular, septic and pulmonary infections. Hence there is interest in the pathogenic determinants of M. nonliquefaciens, of which outer membrane (OM) structures such as fimbriae and two capsular polysaccharide (CPS) structures, →3)-ß-D-GalpNAc-(1→5)-ß-Kdop-(2→ and →8)-α-NeuAc-(2→, have been reported in the literature. To further characterise its surface virulence factors, we isolated a novel CPS from M. nonliquefaciens type strain CCUG 348T. This structure was elucidated using NMR data obtained from CPS samples that were subjected to various degrees of mild acid hydrolysis. Together with GLC-MS data, the structure was resolved as a linear polymer composed of two GalfNAc residues consecutively added to Kdo, →3)-ß-D-GalfNAc-(1→3)-α-D-GalfNAc-(1→5)-α-(8-OAc)Kdop-(2→. Supporting evidence for this material being CPS was drawn from the proposed CPS biosynthetic locus which encoded a potential GalfNAc transferase, a UDP-GalpNAc mutase for UDP-GalfNAc production and a putative CPS polymerase with predicted GalfNAc and Kdo transferase domains. This study describes a unique CPS composition reported in Moraxella spp. and offers genetic insights into the synthesis and expression of GalfNAc residues, which are rare in bacterial OM glycans.

Structure of the K141 capsular polysaccharide produced by Acinetobacter baumannii isolate KZ1106 that carries KL141 at the chromosomal K locus.

The structure of the K141 type capsular polysaccharide (CPS) produced by Acinetobacter baumannii KZ1106, a clinical isolate recovered from Kazakhstan in 2016, was established by sugar analyses and one- and two-dimensional 1H and 13C NMR spectroscopy. The CPS was shown to consist of branched tetrasaccharide repeating units (K-units) with the following structure: This structure was found to be consistent with the genetic content of the KL141 CPS biosynthesis gene cluster at the chromosomal K locus in the KZ1106 whole genome sequence. Assignment of the encoded enzymes allowed the first sugar of the K unit to be identified, which revealed that the ß-d-GlcpNAc-(1→3)-d-GlcpNAc bond is the linkage between K-units formed by the WzyKL141 polymerase.

Review on emerging trends and challenges in the modification of xanthan gum for various applications.

This review explores the realm of structural modifications and broad spectrum of their potential applications, with a special focus on the synthesis of xanthan gum derivatives through graft copolymerization methods. It delves into the creation of these derivatives by attaching functional groups (-OH and -COOH) to xanthan gum, utilizing a variety of initiators for grafting, and examining their diverse applications, especially in the areas of food packaging, pharmaceuticals, wastewater treatment, and antimicrobial activities. Xanthan gum is a biocompatible, biodegradable, less toxic, bioactive, and cost-effective natural polymer derived from Xanthomonas species. The native properties of xanthan gum can be improved by cross-linking, grafting, curing, blending, and various modification techniques. Grafted xanthan gum has excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing ability. Owing to its remarkable properties, such as biocompatibility and its ability to form gels resembling the extracellular matrix of tissues, modified xanthan gum finds extensive utility across biomedicine, engineering, and the food industry. Furthermore, the review also covers various modified derivatives of xanthan gum that exhibit excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing abilities. These applications could serve as important resources for a wide range of industries in future product development.

Optimization and characterization of high internal phase double emulsion (HIPDE) stabilized by with soybean protein isolate, gallic acid and xanthan gum.

This study aims to formulate a stable high internal phase double emulsion (HIPDE) using soybean protein isolate (SPI), gallic acid (GA), and xanthan gum (XG). To prepare HIPDE, W1/O was formulated with the water phase dispersed in the oil phase using polyglycerol polyricinoleate (PGPR) as a stabilizer. Thereafter, W1/O dispersed in W2 (SPI solution) was used. To stabilize the HIPDE, GA was added in W1 (0 or 1 %), XG was added in W2 (0 or 1 %), and the pH of the W phases was adjusted to acidic, neutral, and basic. The samples containing GA in W1 and XG in W2 did not phase out during the storage periods and maintained a higher ζ-potential value, a higher apparent viscosity, and a more sustainable droplet compared to others. These results were derived by the interaction between SPI and XG, SPI and GA, or GA and PGPR. Physicochemical crosslinks were formed, such as gallate-derived groups, SPI-GA complexation (Michael addition, Shiff base reaction), and hydrogen bonding. In conclusion, applying the SPI, GA, and XG to HIPDE would contribute to various industries such as food, medicine, and cosmetics.

Comprehensive review on recent trends and perspectives of natural exo-polysaccharides: Pioneering nano-biotechnological tools.

Exopolysaccharides (EPSs), originating from various microbes, and mushrooms, excel in their conventional role in bioremediation to showcase diverse applications emphasizing nanobiotechnology including nano-drug carriers, nano-excipients, medication and/or cell encapsulation, gene delivery, tissue engineering, diagnostics, and associated treatments. Acknowledged for contributions to adsorption, nutrition, and biomedicine, EPSs are emerging as appealing alternatives to traditional polymers, for biodegradability and biocompatibility. This article shifts away from the conventional utility to delve deeply into the expansive landscape of EPS applications, particularly highlighting their integration into cutting-edge nanobiotechnological methods. Exploring EPS synthesis, extraction, composition, and properties, the discussion emphasizes their structural diversity with molecular weight and heteropolymer compositions. Their role as raw materials for value-added products takes center stage, with critical insights into recent applications in nanobiotechnology. The multifaceted potential, biological relevance, and commercial applicability of EPSs in contemporary research and industry align with the nanotechnological advancements coupled with biotechnological nano-cleansing agents are highlighted. EPS-based nanostructures for biological applications have a bright future ahead of them. Providing crucial information for present and future practices, this review sheds light on how eco-friendly EPSs derived from microbial biomass of terrestrial and aquatic environments can be used to better understand contemporary nanobiotechnology for the benefit of society.

Structural characterization of an exopolysaccharide produced by two strains of Lacticaseibacilluscasei.

Exopolysaccharides (EPSs) were isolated and purified from Lacticaseibacillus casei strains type V and RW-3703M grown under various fermentation conditions (carbon source, incubation temperature, and duration). Identical 1H NMR spectra were obtained in all cases. The molar mass determined by size-exclusion chromatography coupled with multi-angle light scattering was different for the two strains and in different culture media. The primary structure was elucidated using chemical and spectroscopic techniques. Monosaccharide and absolute configuration analyses gave the following composition: d-Glc, 1; d-Gal, 2; l-Rha, 2; d-GlcNAc, 1. Methylation analysis indicated the presence of 4-linked Glc, terminal and 6-linked Gal, terminal and 3-linked Rha, and 3,4,6-linked GlcNAc. On the basis of one- and two-dimensional 1H and 13C NMR data, the structure of the EPS was consistent with the following hexasaccharide repeating unit: {4)[Rhap(α1-3)][Galp(α1-6)]GlcpNAc(ß1-6)Galp(α1-3)Rhap(ß1-4)Glcp(ß1-}n. Complete 1H and 13C NMR assignments are reported.

The exopolysaccharides produced by Leuconostoc mesenteroides XR1 and its effect on silk drawing phenomenon of yoghurt.

Yoghurt fermented by Leuconostoc mesenteroides XR1 from Kefir grains was found to produce a unique silk drawing phenomenon. This property was found to be associated with the exopolysaccharides (EPS), X-EPS, produced by strain XR1. In order to better understand the mechanism that produced this phenomenon, the X-EPS was extracted, purified and characterized. The molecular weight and monosaccharide composition were determined by size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and ion chromatography (IC) analysis, respectively. The results showed that its molecular weight was 4.183 × 106 g/mol and its monosaccharide composition was glucose, and glucuronic acid, with the contents of 567.6148 and 0.2096 µg/mg, respectively. FT-IR and NMR analyses showed that X-EPS was an α-pyranose polysaccharide and was composed of 92.22 % α-(1 â†’ 6) linked d-glucopyranose units and 7.77 % α-(1 â†’ 3) branching. Furthermore, it showed a chain-like microstructure with branches in atomic force microscopy (AFM) and scanning electron microscopy (SEM) experiments. These results suggested that the unique structure of X-EPS, gave the yoghurt a strong viscosity and cohesiveness, which resulted in the silk drawing phenomenon. This work suggested that X-EPS holds the potential for food and industrial applications.

Effect of Lactobacillus helveticus exopolysaccharides molecular weight on yogurt gel properties and its internal mechanism.

The processing characteristics of yogurt are closely related to the composition and arrangement of exopolysaccharides (EPS) in lactic acid bacteria (LAB). To fully understand and develop the functional properties of EPS and to study the effect of EPS molecular weight on yogurt and its mechanism, the physicochemical properties of high molecular weight EPS-LH43, medium molecular weight EPS-LH13, and low molecular weight EPS-LH23, as well as the gel properties and protein conformation of yogurt, were determined and analyzed in this experiment. The results indicate that EPS-LH43 and EPS-LH13 are both composed of mannose, rhamnose, galacturonic acid, glucose, and galactose. EPS-LH23 is composed of mannose, galacturonic acid, glucose, and galactose. Their Number-average Molecular Weight is 5.21 × 106 Da, 2.39 × 106 Da and 3.76 × 105 Da, respectively. In addition, all three types of EPS have good thermal stability and can improve the stability of casein. In addition, the analysis of the texture, particle size, potential, water holding capacity, rheology, low field nuclear magnetic resonance, microstructure, and flavor characteristics of yogurt confirmed the relationship between the molecular weight of LAB EPS and the gel properties of yogurt. Fluorescence spectrophotometer and circular dichroism analysis indicate that the different molecular weights of LAB EPS have different effects on protein structure, which is an intrinsic factor leading to significant differences in the gel properties of the three types of fermented milk. These findings provide new references for enhancing the understanding of the structure-activity relationship of EPS and indicate that EPS-LH43 can be used to improve the gel properties of dairy products.

The Acinetobacter baumannii K239 capsular polysaccharide includes heptasaccharide units that are structurally related to K86 but joined by different linkages formed by different Wzy polymerases.

The K239 type capsular polysaccharide (CPS) isolated from Acinetobacter baumannii isolate MAR19-4435 was studied by sugar analysis, one- and two-dimensional 1H and 13C NMR spectroscopy. K239 consists of branched heptasaccharide repeats (K-units) comprised of five residues of l-rhamnose (l-Rhap), and one residue each of d-glucuronic acid (d-GlcpA) and N-acetyl-d-glucosamine (d-GlcpNAc). The structure of K239 is closely related to that of the A. baumannii K86 CPS type, though the two differ in the 2,3-substitution patterns on the l-Rhap residue that is involved in the linkage between K-units in the CPS polymer. This structural difference was attributed to the presence of a gtr221 glycosyltransferase gene and a wzyKL239 polymerase gene in KL239 that replaces the gtr80 and wzyKL86 genes in the KL86 CPS biosynthesis gene cluster. Comparison of the two structures established the role of a novel WzyKL239 polymerase encoded by KL239 that forms the ß-d-GlcpNAc-(1→2)-l-Rhap linkage between K239 units. A. baumannii MAR19-4435 was found to be non-susceptible to infection by the APK86 bacteriophage, which encodes a depolymerase that specifically cleaves the linkage between K-units in the K86 CPS, indicating that the difference in 2,3-substitution of l-Rhap influences the susceptibility of this isolate to bacteriophage activity.

Development of Biological Coating from Novel Halophilic Exopolysaccharide Exerting Shelf-Life-Prolonging and Biocontrol Actions for Post-Harvest Applications.

The literature presents the preserving effect of biological coatings developed from various microbial sources. However, the presented work exhibits its uniqueness in the utilization of halophilic exopolysaccharides as food coating material. Moreover, such extremophilic exopolysaccharides are more stable and economical production is possible. Consequently, the aim of the presented research was to develop a coating material from marine exopolysaccharide (EPS). The significant EPS producers having antagonistic attributes against selected phytopathogens were screened from different marine water and soil samples. TSIS01 isolate revealed the maximum antagonism well and EPS production was selected further and characterized as Bacillus tequilensis MS01 by 16S rRNA analysis. EPS production was optimized and deproteinized EPS was assessed for biophysical properties. High performance thin layer chromatography (HPTLC) analysis revealed that EPS was a heteropolymer of glucose, galactose, mannose, and glucuronic acid. Fourier transform infrared spectroscopy, X-ray diffraction, and UV-visible spectra validated the presence of determined sugars. It showed high stability at a wide range of temperatures, pH and incubation time, ≈1.63 × 106 Da molecular weight, intermediate solubility index (48.2 ± 3.12%), low water holding capacity (12.4 ± 1.93%), and pseudoplastic rheologic shear-thinning comparable to xanthan gum. It revealed antimicrobial potential against human pathogens and antioxidants as well as anti-inflammatory potential. The biocontrol assay of EPS against phytopathogens revealed the highest activity against Alternaria solani. The EPS-coated and control tomato fruits were treated with A. solani suspension to check the % disease incidence, which revealed a significant (p < 0.001) decline compared to uncoated controls. Moreover, it revealed shelf-life prolonging action on tomatoes comparable to xanthan gum and higher than chitosan. Consequently, the presented marine EPS was elucidated as a potent coating material to mitigate post-harvest losses.

Modification of Welan gum with poly(2-oxazoline) to obtain thermoviscosifying polymer for enhanced oil recovery.

Thermoviscosifying polymers refer to a category of smart materials that exhibit a responsive behavior to environmental stimuli, specifically demonstrating a natural rise in viscosity of solutions as the temperature increases. The temperature-dependent behavior exhibited by thermally viscous polymers renders them potentially advantageous in the context of Enhanced Oil Recovery (EOR). There exists a dearth of research pertaining to the application of thermoviscosifying polymer for better recovery in reservoirs characterized by high temperatures and high salt content. In order to tackle the mentioned concerns, this study examined the utilization of welan gum modified with poly(2-oxazoline) as thermally responsive chain segments to enhance viscosity. The objective was to evaluate the ability to enhance viscosity under thermal conditions and to assess their effectiveness in displacement of reservoir oil in high temperature and high salt environments. This study aimed to establish a theoretical framework for understanding the correlation between the molecular structure and performance of novel thermally viscous polymers. Additionally, it sought to offer practical insights into designing the molecular structure of thermally viscous polymers suitable for polymer flooding in high temperature and high salt environments. Furthermore, the study proposed the application of these new thermoviscosifying polymers for EOR.

Synthesis of 6-deoxy-d-ido-heptopyranose-containing fragments of the Campylobacter jejuni strain CG8486 capsular polysaccharide.

Campylobacters are important causes of gastrointestinal illness and the capsular polysaccharides (CPS) they produce are key virulence factors and targets for vaccine development. We report here the synthesis of two fragments of the Campylobacter jejuni CG8486 strain CPS that contain a rare 6-deoxy-d-ido-heptopyranose residue and, in one target, two O-methyl phosphoramidate (MeOPN) motifs. The synthetic approach features the stereoselective construction of the ß-d-ido-heptopyranoside linkage via glycosylation with a ß-d-galacto-heptopyranoside donor followed by a one-pot sequential C-2 and C-3 inversion. During the syntheses, we uncovered a number of interesting conformational effects with regard to the 6-deoxy-ido-heptopyranose ring, the glycosidic linkage connecting the two monosaccharides, and the MeOPN groups.

Bioactive foamulsion gels: a unique structure prepared with gellan gum and Acanthophyllum glandulosum extract.

BACKGROUND: Foamulsions have become increasingly popular in the food industry due to their ability to enhance the textural, sensory and health-promoting properties of food products. This study was therefore aimed to design and prepare a novel gelled structure, foamulsion gel containing 0-600 g L-1 oil, with gellan gum (GG; 7, 10 and 13 g L-1) and saponin-rich antioxidant Acanthophyllum glandulosum extract (AGE; 2, 6 and 10 g L-1). RESULTS: The interaction between components was confirmed by infrared spectroscopy. The overrun and porosity of the foamulsion gels increased with antioxidant AGE (1.30 times) and reduced with oil (up to ca 70% and 30%, respectively) and GG levels. The systems were highly stable, and no water or oil was released during the physical stability experiments. Microscopic images showed that the size of air cells was significantly larger than that of oil droplets. The foamulsion gels based on 13 g L-1 GG and 10 g L-1 AGE had markedly higher elastic (G') and viscous (G'') moduli than other samples, and exhibited an elastic and solid-like behavior (G' > G''). The highest gel firmness was found in oil-free sample, and the presence of oil resulted in a lower firmness induced by the larger size and lubrication effect of oil droplets. CONCLUSION: As a result, the interactions between AGE, GG and oil could lead to the creation of new aerated structures known as bioactive foamulsion gels. These gels exhibit excellent foamability, stability and viscoelasticity and may find applications in the development of novel, healthy and low-calorie aerated foods. © 2024 Society of Chemical Industry.

Physicochemical properties and stability of oil-in-water emulsions stabilized by soy protein isolate and xanthan gum.

The aim of this work was to determine rheological and disperse characteristics and stability of oil-in-water emulsions stabilized by soy protein isolate (SPI) and xanthan gum (XG), as natural components. The effects of their combination on emulsion stabilization have not been investigated yet. The existence of interactions between the two macromolecules were indicated by the influence of XG on SPI surface hydrophobicity and surface tension values. Increase in SPI concentration from 1 to 3 % shift of distribution curves towards smaller particle size, while the opposite effects of further increase of SPI was obtained. The emulsions stabilized by SPI showed shear-thinning flow behavior, which changed to thixotropic at 5 % of SPI concentration. The presence of XG in emulsions at low concentrations did not affect the size distribution of the droplets, while at 0.1 % of XG Sauter mean diameter value raised and distribution curves were shifted towards a higher particle size. The presence of XG at higher concentration resulted in thixotropic flow behavior of emulsions. Also, increase in XG concentration led to the increase in consistency index and extent of non-Newtonian behavior of emulsions and enhanced the influence of the elastic modulus and creaming stability of the systems.

Effect of black wolfberry anthocyanin and maltitol on the gelation and microstructural properties of curdlan/gellan gum hybrid gels.

BACKGROUND: Laboratory scale experiments have shown that curdlan and gellan gum gelled together as curdlan/gellan gum (CG) hybrid gels showed better gel properties than the individual curdlan and gellan gum. In this study, CG and black wolfberry anthocyanin (BWA), CG and maltitol (ML) hybrid gels were constructed using CG hybrid gel as matrix. The effects of BWA or ML on the gel properties and microstructure of CG hybrid gels were investigated and a confectionery gel was developed. RESULTS: The presence of BWA increased the storage modulus (G') value of CG at 0.1 Hz, whereas ML had little effect on the G' value of CG. The addition of BWA (5 g L-1 ) and ML (0.3 mol L-1 ) increased the melting and gelling temperatures of CG hybrid gels to 42.4 °C and 34.1 °C and 44.2 °C and 33.2 °C, respectively. Meanwhile, the relaxation time T22 in CG-ML and CG-BWA hybrid gels was reduced to 91.96 and 410.27 ms, indicating the strong binding between BWA and CG, ML and CG. The hydrogen bond interaction between BWA or ML and CG was confirmed by the shift in the hydroxyl stretching vibration peak. Moreover, the microstructures of CG-ML and CG-BWA hybrid gels were denser than that of CG. In addition, confectionery gel containing CG-BWA-ML has good chewing properties. CONCLUSION: These results indicated that the incorporation of BWA or ML could improve the structure of CG hybrid gels and assign a sustainability potential for the development of confectionery gels based on CG complex. © 2024 Society of Chemical Industry.

Epoxide-Mediated Trans-Thioglycosylation and Application to the Synthesis of Oligosaccharides Related to the Capsular Polysaccharides of C. jejuni HS:4.

The enzyme-resistant thioglycosides are highly valuable immunogens because of their enhanced metabolic stability. We report the first synthesis of a family of thiooligosaccharides related to the capsular polysaccharides (CPS) of Campylobacter jejuni HS:4 for potential use in conjugate vaccines. The native CPS structures of the pathogen consist of a challenging repeating disaccharide formed with ß(1→4)-linked 6-deoxy-ß-D-ido-heptopyranoside and N-acetyl-D-glucosamine; the rare 6-deoxy-ido-heptopyranosyl backbone and ß-anomeric configuration of the former monosaccharide makes the synthesis of this family of antigens very challenging. So far, no synthesis of the thioanalogs of the CPS antigens have been reported. The unprecedented synthesis presented in this work is built on an elegant approach by using ß-glycosylthiolate as a glycosyl donor to open the 2,3-epoxide functionality of pre-designed 6-deoxy-ß-D-talo-heptopyranosides. Our results illustrated that this key trans-thioglycosylation can be designed in a modular and regio and stereo-selective manner. Built on the success of this novel approach, we succeeded the synthesis of a family of thiooligosaccharides including a thiohexasaccharide which is considered to be the desired antigen length and complexity for immunizations. We also report the first direct conversion of base-stable but acid-labile 2-trimethylsilylethyl glycosides to glycosyl-1-thioacetates in a one-pot manner.